Organizational, time management and planning (OTMP) skills deficits are seriously impairing features of Attention-Deficit/Hyperactivity Disorder (ADHD) that compromise school performance and family relations. There have been minimal advancements in the treatment of OTMP deficits in child with ADHD. Via an R21 grant we conducted a research program aimed at remedying organizational skills deficit in children with ADHD. To this end, we: 1) developed assessments to quantify OTMP deficits in children with ADHD, 2) developed a 10-week, 20-session manualized organizational skills training (OST) program designed to target children's specific OTMP deficits, and 3) conducted a pilot study to generate estimates of effect for this novel intervention. Our open pilot study demonstrated treatment feasibility, satisfaction with treatment, and significant improvements in OTMP behaviors at school and home. Findings provide a basis for a larger test of the intervention through a randomized controlled trial. This application proposes a dual-site (NYU and Duke) efficacy study of OST in 180 children with ADHD and organizational skills deficits, ages 8-11, in grades 3-5, randomized to one of three conditions: OST (N = 72), Contingency Management (CM;N = 72), or Wait List (WL;N = 36). The study is designed to control for 1) simple contingency management with target tasks, without organizational skills training, 2) time, and 3) repeat assessments. Treatment contrasts will examine children's 1) OTMP skills, 2) academic planning skills, 3) academic performance, 4) homework behaviors, 5) report card grades, 6) attitudes toward school and teachers, 7) family relationships, and 8) treatment satisfaction. It is predicted that OST will be superior to WL control and CM. We will evaluate children's long-term function, and hypothesize that at one-month follow-up, as well in the next grade, children provided with OST will demonstrate significantly better organizational skills compared to those who received CM. The impact of parents'ADHD symptomatology on their treatment implementation and child outcomes will be explored. If successful, the study will be a major advance in the treatment of children with ADHD, and provide the field with an intervention that addresses one of the more vexing clinical features of the disorder.